1. Field of the Invention
This invention most generally relates to an apparatus and method for perforating pipe. More particularly, the invention relates to the perforating of pipe from the inside of the pipe to the outside of the pipe. More particularly, the invention relates to the perforating of corrugated plastic pipe by passing a section of corrugated plastic pipe over a cutter or by advancing the perforating cutter into the interior of the pipe, the cutter cutting perforations in the pipe as the pipe is passed over the cutter or the cutter is inserted into the pipe.
The invention has the particular objectives, advantages and features of: 1) increased cutting speed; 2) size of notches being cut can be changed more readily; 3) multiple notches can be cut using the same cutter; 4) more efficient; 5) slots may be round holes or non-round; 6) indexing for the number of holes or slots may be more easily accomplished; 7) can be set up to do spiral cutting from the inside so as to not weaken the strength of the pipe in any location as to the extent that it would happen with slots cut in the same location along the piece of pipe; 8) allows for pipe to be stored without perforations, and then perforated as needed; 9) various bits, saws, blades, and routers can be employed; 10) major components readily available; 11) Half the perforations may be cut on the way in and half on the way out.
2. Description of the Prior Art
Many drainage pipes are produced from plastic materials, either by extrusion or blow molding, with the pipe being cut into lengths or rolled on a large drum to be carded in the field. To obtain high rigidity and maximum utilization of material, such drainage pipes are commonly corrugated with the corrugations extending circumferentially around the pipe. Corrugated plastic pipe is widely used for many types of domestic, agricultural, and industrial drainage and waste disposal systems.
Preferably, drainage holes are positioned in the wall of the inner corrugation so that, when the pipe is ultimately buried in the earth, the drainage holes are not packed as tightly as would be the case if they were positioned in the outer corrugation. Having the perforations on the inner corrugation facilitates drainage from the pipe, but, for obvious reasons, complicates the formation of the perforations.
It is therefore desirable to have an effective apparatus and method for creating perforations on the inner corrugation or valley portions of a corrugated pipe. All of the perforating machines and methods for perforating the pipe known by the inventor hereof, perforate, drill or punch the holes or apertures from the outside of the pipe to the inside of the pipe. Such curing is inherently slow and cumbersome. Various cutters or punches have been used in the prior art to perforate the inner corrugation.
The following patents relate to the technology of the present invention, but none of them meets the objects of the presently disclosed and claimed invention. Additionally, none are as effective and as efficient as the instant apparatus and method.
U.S. Pat. No. 4,587,874 to Lupke, et. al. discloses a rotary punch. The rotary punch is a spindle carrying a cutting tool and a drive for rotating the spindle about its own axis while revolving the spindle about the pipe. The cutter periodically engages and perforates the pipe.
U.S. Pat. No. 4,204,447 to Slaughterbeck discloses an apparatus for perforating corrugated plastic pipe. The Slaughterbeck apparatus employs a plurality of reciprocally moving heated punches which punch radially into the pipe and are then removed to form perforations. The pipe is then translated to another position for the next punching step.
U.S. Pat. No. 4,180,357 to Lupke, et. al. discloses an apparatus and method for perforating pipe and method of producing part of such apparatus. The Lupke apparatus advances corrugated pipe along its axial path by rotatably driven lead screw members, the screw threading of which is in meshing engagement with the corrugations of the pipe. The lead screw members present outwardly directed cutters which are synchronized to simultaneously intersect the pipe thereby creating perforations.
U.S. Pat. No. 4,104,942 to Leloux discloses a device for manufacturing perforated plastic pipes. Disclosed is a device having at least one punching member, to which a velocity is imparted in the direction of conveyance of the plastic pipes. During the punching operation, the punching members remain substantially perpendicular with respect to the plastic pipes.
U.S. Pat. No. No. 3,916,763 to Maroschak discloses an apparatus for forming slits in tubes. The Maroschak apparatus an improved means of feeding a tube through a slitting station in a stepwise manner, wherein rotary cutting blades and moved into and out of cutting engagement with the tube between successive stepwise movements thereof.
U.S. Pat. No. 3,901,113 to Oltmanns, et. al. discloses a device to cut holes within the wave troughs of a corrugated tube, especially for drainage. The device employs tool supports geared with the waves of the tube. The tube and tool support are synchronized.
U.S. Pat. No. 3,877,831 to Maroschak discloses a method and apparatus for drilling holes in tubes. The tube is fed through a drilling station where one or more longitudinal rows are drilled in the wall of the tube by means of a corresponding number of rotating drill bits. The drilling station includes a separate drilling head for forming each row of holes. Each of the drilling heads is rotated in timed relation to the movement of the tube so as to drill holes therein without interrupting or retarding the movement of the tube.
U.S. Pat. No. 3,831,470 to Maroschak discloses a method and apparatus for forming slits in tubes. Maroschak discloses intermittently feeding the tube through a slitting station in a stepwise manner and moving a plurality of rotating cutting blades which encircle the path of travel of the tube into cutting engagement with the tube between successive stepwise movements. The apparatus includes a pair of rotary feed members which engage portions of the tube closely adjacent sets of rotary cutting blades arranged around the path of travel of the tube, and means for imparting stepwise movement to the tube in timed relation to the inward and outward movements of the cutting blades. U.S. Pat. No. 3,824,886 to Hegler discloses an apparatus for cutting apertures in tubes. The Hegler apparatus employs means for revolving a cutter about the pipe to be cut in cooperation with a means for moving the cutting surface in an epitrochoid path as it passes through the exterior surface.
U.S. Pat. No. 3,698,222 to Blake discloses a perforating machine. The Blake machine employs a rotating punch and die roll means in cooperation with corrugated roll means. The punch roll being formed of disks separated by spacers.
The patents noted herein provide considerable information regarding the developments that have taken place in this field of technology. Clearly, the present invention provides many advantages over the inventions noted above. Again it is noted that none of the inventions listed above cuts from the inside of the pipe to the outside. As such, none is as effective or efficient as the present invention.
By cutting corrugated pipe from the inside, it is not required that the pipe be perforated in a stepwise manner. Rather, the pipe can be advanced over the insertable perforating means in a substantially continuous motion or the pipe may be stationary and the perforating means or cutter head may be moved into the interior of the pipe. It is also possible to create another set of perforations while removing the pipe from about the perforating means or extracting the perforating device from within the pipe. The pipe may be rotated after the initial advancement over the perforating means and before the pipe is removed from about the perforating means to create different set of perforations. Alternatively, the pipe may be rotated as it is advanced over the perforating means so as to create a perforation pattern which is non-linear. The non-linear perforation pattern can be a spiral pattern by continuously rotating the pipe as it is advanced over the perforating means. It should also be obvious that there may be advantage to have different size holes and a non-symmetric hole pattern in the pipe. All of these variations are easily achieved with the instant apparatus and method.
Additionally, the present invention may include a gear trailing the perforating means in such a way as to have the cutters move in and out, thereby making alternate cuts on possibly every other rib of the corrugated pipe or detent as it travels along. More than one rib could be skipped.
The present invention may also be employed to perforate pipe as it comes off an extruder. This embodiment would employ a trailing wire, a flexible shaft, or conduit coming from the extruder to the perforating means which would also hold onto the cutting head and supply power at the same time to run the cutters. Obviously, this operation would take place at a sufficient distance and time from the extrusion process to allow the plastic to cool. The result would be that as the pipe slides over the cutters, which would be held in place by cable or wire, it would cut the notches which are desired within the pipe, and could use the above methods of gearing for cutting notches and slots and spiraling within the pipe or skipping detents within the pipe as necessary. This embodiment could produce virtually any length or an endless length of perforated pipe.
The perforated pipe which is produced by the present invention is distinctive due to having been cut from the inside out thereby creating apertures or holes which could be identified as being made from inside to outside the pipe. The perforations in the perforated pipe produced by the present invention may be of various shapes. For example, the perforations may be round or slotted.